Dank Karel!
@ Adrie. Idd. ons gebied is nog steeds te lastig. Maar ondertussen zijn er wel steeds stapjes in de goede richting.Zie onderzoek van Adam Scaife van UKMO.
http://www.rmets.org/sites/default/files/event_documents/4/se_centre_scaife.pdfhttp://onlinelibrary.wiley.com/doi/10.1002/2014GL059637/abstractUiteraard is er ook kritiek. Die deels lijkt op de feedback naar Cohen.
In this regard, Scaife et al., 20142 have recently shown that the new UK Met Office seasonal forecast model Global Seasonal forecast system version 5 (GloSea5) was able to skillfully predict the wintertime North Atlantic Oscillation (NAO) index for the period 1993–2012, due a considerable increase in resolution. However, due to the limited length of the hindcast period used, this finding has provoked much controversy, since the estimates of skill measure based on small verification time series can have large departures from their expected value because of sampling errors (Kumar et al., 20093).
For instance, Shi et al., 20154 have shown that sampling uncertainty due to the length of the hindcast period is large. In particular, they found, using a combination of models from the DEMETER and ENSEMBLES projects, that the skill for forecasting the NAO during winter varies within the 40 year data sets with high levels of skill found for some subperiods. They demonstrated that while 20 year estimates of seasonal reliability can show evidence of overdispersive behavior, the 40 year estimates are more stable and show no evidence of overdispersion, indicating that a 20 year period may be insufficient for a robust estimation of overall predictive skill (which is in agreement with previous results from Muller et al., 20055).
Uiteindelijk blijft het wel een verrassing, al vind ik dat een stuk minder dan vroeger. Wie de ontwikkelingen volgt zal bijv. vorig jaar november weinig reden tot hoop hebben gehad.